Pyridine‐ and Imidazoledicarboxylates of Zinc: Hydrothermal Synthesis, Structure, and Properties

Abstract The reaction of hetrocyclic dicarboxylic acids, such as pyridine‐2,5‐dicarboxylic acid and imidazole‐4,5‐dicarboxylic acid, under hydrothermal conditions in the presence of an appropriate zinc salt yields three new zinc coordination polymers 0 ∞ [{Zn 2 (H 2 O) 4 }{C 5 H 3 N(COO) 2 } 2 ] ( 1 ), 1 ∞ [{Zn(C 12 H 8 N 2 )}{C 5 H 3 N(COO) 2 } · 0.5H 2 O] ( 2 ), and 1 ∞ [{Zn(C 12 H 8 N 2 )}{C 3 HN 2 (COO) 2 }] ( 3 ). While 1 forms with a zero‐dimensional molecular rectangular box structure, 2 and 3 have zig‐zag one‐dimensional chain structures. The Zn 2+ ions are coordinated by both the carboxylate oxygen atoms and also by the nitrogen atoms of the heterocycles. The 1,10‐phenanthroline molecules in 2 and 3 act as a secondary ligands and occupy the inter‐chain spaces. The moderate hydrogen‐bond interaction energy in 1 and the π ··· π interactions in 2 and 3 appear to play an important role for the structural stability. The structures of 2 and 3 appear to be related, even though they are formed with different carboxylic acids. All three compounds exhibit photoluminescence at room temperature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)